采用高低阀接线的嵌套型MMC拓扑及其直流故障穿越策略  

Topology and DC Fault Ride-through Strategy of Embedded Modular Multilevel Converter with High-/low-voltage Valve Connection

作　　者：张紫如 付丰豪 赵西贝 贾秀芳 ZHANG Ziru;FU Fenghao;ZHAO Xibei;JIA Xiufang(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Beijing 102206,China;High Voltage Branch of State Grid Tianjin Electric Power Company,Tianjin 300232,China)

机构地区：[1]新能源电力系统全国重点实验室(华北电力大学),北京市102206 [2]国网天津市电力公司高压分公司,天津市300232

出　　处：《电力系统自动化》2024年第16期154-164,共11页Automation of Electric Power Systems

基　　金：国家自然科学基金资助项目(52307097)。

摘　　要：在采用高低阀接线的半桥型模块化多电平换流器(MMC)特高压远距离直流输电系统中,故障清除所需的特高压直流断路器尚不成熟,并且成本较高。针对上述问题,文中提出一种采用高低阀接线的嵌套型MMC拓扑。参考全桥子模块运行的基本原理,设计辅助高阀MMC进行电压极性反转的外嵌桥臂、内嵌能量转移支路,使半桥型MMC换流站实现较混合型MMC成本更低的无闭锁直流故障穿越。根据故障清除期间各支路的通断时序与不同器件的通断用时,设计了故障穿越控制策略。通过对各阶段器件的电流、电压应力进行分析,为器件提供选型与数目配置依据。最后,利用PSCAD/EMTDC仿真验证所提策略的有效性,并将器件成本和运行损耗与现有MMC方案进行对比,证明了所提方案更具经济优势。In the ultra-high-voltage and long-distance DC transmission system using the half-bridge modular multilevel converter(MMC)with high-/low-voltage valve connection,the ultra-high-voltage DC circuit breakers required for fault clearance are immature and costly.Aiming at the above problems,this paper proposes an embedded MMC topology with high-/low-voltage valve connection.According to the basic principle of full-bridge sub-module operation,an external embedded bridge arm and an internal embedded energy transfer branch are designed to reverse the voltage polarity of the MMC with the high-voltage valve.The converter station of the half-bridge MMC can realize the non-blocking DC fault ride-through with a lower cost than that of the hybrid MMC.Based on the switching sequence of each branch and the switching time of different devices during fault clearing,the fault ride-through control strategy is designed.By analyzing the current and voltage stress of the device in each stage,the basis for device selection and number configuration is given.Finally,the effectiveness of the proposed control strategy is verified by PSCAD/EMTDC simulations.The device cost and operation loss of the proposed strategy are compared with the existing MMC schemes,which shows the proposed strategy is more economical.

关 键 词：柔性直流输电 模块化多电平换流器 故障穿越 故障等效模型 

分 类 号：TM721.1[电气工程—电力系统及自动化]